Perovskite solar panels could become more efficient and sturdier over longer periods by engineering the nanoscale structure of perovskite devices, claims a new study by a team of scientists from the Massachusetts Institute of Technology and other institutions.

Perovskites are materials with a special crystal structure that may one day outperform conventional silicon or cadmium telluride solar cells, according to a study published in the journal Nature Energy. A major advantage is that perovskites can be solution-processed and essentially painted or printed onto surfaces like flexible plastic, paper, or glass, making them versatile and easy to transport.

However, the challenge is the relatively short operating life of perovskite solar cells compared to silicon. Perovskites break down in months rather than decades. Their efficiency also lags slightly behind silicon over large areas.

The researchers said optimizing the surface properties of perovskites using nanoscale surface engineering can control defects that cause energy losses, extending the lifetime and boosting efficiency.

“This paper is essentially revealing a guidebook for how to tune surfaces, where a lot of these defects are, to make sure that energy is not lost at surfaces,” said co-author of the paper Dane deQuilettes. “This is the first paper that demonstrates how to systematically control and engineer surface fields in perovskites.”

The key is using a salt solution treatment that forms an ultra-thin coating to “passivate” or modify the defective surface layer of the perovskite crystal.

This restructures the surface to reduce defects where electrons can become trapped and lose energy. Electrons can travel more efficiently through the bulk perovskite toward electrodes.

The insights pave the way for further efficiency gains in perovskite solar panels, which have recently reached 24-26% efficiency in the lab versus a maximum theoretical limit of 30%.

“I think we are on the doorstep of the first practical demonstrations of perovskites in the commercial applications,” MIT professor Vladimir Bulovic said. “And those first applications will be a far cry from what we’ll be able to do a few years from now.”

Recently, researchers at the University of Michigan found that perovskites may be combined with silicon-based semiconductors to create “tandem” solar cells that can surpass the maximum theoretical efficiency of silicon solar cells. This could further enable solar cells to be two to four times cheaper when compared to thin-film solar cells.